Method for managing recorded streams in a rewritable recording medium

ABSTRACT

The present invention relates to a method for managing playlists of a rewritable recording medium in order to prevent unlimited playback or illegal edition of television broadcast programs or movies wherein copyright protection is required. The present invention operates by adding information needed for automatic timed deletion of consecutively recorded clips of A/V streams and deletion time information into the playlists of a recording medium such as a high density rewritable optical disc (BD-RW), whereby referring to the recorded information, the corresponding clips of A/V streams are automatically deleted.

This application is a Divisional of co-pending application Ser. No.10/446,852 filed on May 29, 2003 and for which priority is claimed under35 U.S.C. § 120. Application No. Korea 2002-0031749 filed on Jun. 5,2002 under 35 U.S.C. § 371. The entire contents of each of theabove-identified applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for automatic timed deletionof video and audio streams stored in a recording medium such as arewritable optical disc.

2. Description of the Related Art

Recently, in accordance with rapid advancement of standardization of anovel high density rewritable recording medium such as ‘Blu-ray DiscRewritable’ (hereinafter referred to as BD-RW) where high quality videoand audio data can be recorded for many hours, it is expected thatrelated products will soon be developed and released to consumer market.

FIG. 1 illustrates a partial structure of an optical disc apparatus suchas a video disc recorder (VDR) which records signals in a recordingmedium such as BD-RW or plays signals thereof. The optical discapparatus may comprise an optical pickup 2 to read out recorded signalsfrom the recording medium such as BD-RW 1 or to record processed datastreams from external inputs; a VDR system 3 to process signals read outfrom the optical pickup 2 for playback or to transform external datastreams into those suitable for recording; and an encoder 4 to encodeanalog signals from external sources to output to the VDR system 3.

As illustrated in FIG. 2, clips of A/V streams recorded in the BD-RW 1,for example, a first clip of A/V stream (Clip 1 A/V Stream) and a secondclip of A/V stream (Clip 2 A/V Stream), each of which is recordedconsecutively are managed by a first real playlist (Real PlayList 1) anda second real playlist (Real PlayList 2) generated automatically at thetime of recording respective A/V streams, wherein respective playcontrol information to read out and play are contained.

In addition, a playlist enabling access to sections selectively chosenfrom a part or whole of the A/V stream clips recorded in said manner canbe generated, which is termed as a virtual playlist. Referring to FIG.2, within the virtual playlist, a playitem of a main path (PlayItem) toread out and play the first clip of A/V stream associated with the firstreal playlist and a sub playitem of a subpath (Sub PlayItem) to read outand play the second clip of A/V stream associated with the second realplaylist can be recorded and managed.

Accordingly, while performing a series of play operations of reading outand playing the first clip of A/V stream managed by the first realplaylist, the optical disc apparatus of VDR system 3 can select and playthe second clip of A/V stream managed by the second real playlist uponuser request.

On the other hand, the VDR system 3, in response to user request, maydelete or edit a part of the first clip of A/V stream or second clip ofA/V stream. As depicted in FIG. 3, in case a part of the second clip ofA/V stream is deleted, the remaining part of the partially deleted A/Vstream is broken up into an A/V stream of second clip and an A/V streamof third clip with corresponding second real playlist and third realplaylist generated and further managed, wherein play control informationto read out and play the A/V streams are incorporated.

In order to allow a user to randomly select, edit and play realplaylists managed by said procedure, a virtual playlist is generated andrecorded, wherein the playitem of the main path to read out and play theA/V stream of first clip associated with the first real playlist and subplayitem of the sub path to read out and play the A/V stream of thirdclip associated with the third real playlist can be recorded and managedat the same time. Consequently, in response to user request, the VDRsystem 3 of the optical disc apparatus, while performing a series ofplay operations of reading out and playing the A/V stream of the firstclip associated with the first real playlist, can select and play theA/V stream of the third clip associated with the third real playlist.

Because the optical disc apparatus as described, in response to userrequest, allows random editing of recorded clips of A/V streams andplaying clips of the A/V streams, however, user's unlimited playback orillegal editing of proprietary television programs or movies are madepossible, where copyright protection and payment are essential.Presently, however, an effective means to prohibit such behavior is yetto be prepared.

SUMMARY OF THE INVENTION

By taking said aspect into account, an embodiment of the presentinvention is directed to providing means for automatic timed deletion ofclips of A/V streams in order to protect copyright and to secure paymentfor proprietary television programs and movies which are recorded in arecording medium such as a high density optical disc (BD-RW). Theembodiment provides a method for managing recorded streams in arewritable recording medium, thereby user's unlimited playback orillegal editing of digital contents recorded in a recording medium canbe prohibited, where copyright protection is required.

A method of managing recorded streams in a rewritable recording mediumto achieve the objective in accordance with an embodiment of the presentinvention is characterized in that it comprises the following steps:recording a clip of data stream with time continuity in a rewritablerecording medium; and recording additional management information in aplaylist in order for automatic deletion of the clip of data streamafter predetermined time.

Another method for managing recorded streams in a rewritable recordingmedium according to an embodiment of the present invention ischaracterized in that it comprises the following steps: searching forand checking an automatic deletion flag and deletion time informationincluded in a playlist corresponding to a clip of data stream recordedwith time continuity in a rewritable recording medium; and determiningto conduct an automatic deletion of the clip of data stream withreference to the automatic deletion flag and deletion time information.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate the preferred embodiments ofthe invention, and together with the description, serve to explain theprinciples of the present invention.

In the drawings:

FIG. 1 is a diagram illustrating a partial structure of an optical diskapparatus such as a video disk recorder (VDR);

FIG. 2 and FIG. 3 are diagrams depicting a situation wherein clips ofA/V streams recorded in a rewritable optical disc, including associatedreal playlists and a virtual playlist;

FIG. 4 is a diagram illustrating a file structure of a rewritableoptical disc;

FIG. 5 is a diagram illustrating a syntax of a real playlist with anautomatic deletion flag recorded by a method for managing recordedstreams according to an embodiment of the present invention; and

FIG. 6 is a diagram illustrating an operational flowchart of a methodfor managing recorded streams in a rewritable recording medium accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention formanaging recorded streams in a rewritable recording medium will bedescribed in detail with reference to appended drawings.

FIG. 4 is a diagram showing the file structure of a rewritable opticaldisc, such as a BD-RW. As shown in FIG. 4, the BD-RW may employ a filestructure, which may include a root directory at the top of the filestructure; at least one DVR directory beneath the root directory; an‘info.dvr’ file, ‘menu.tidx’ files, and ‘mark.tidx’ files under each DVRdirectory; a PLAYLIST subdirectory where multiple real and virtualplaylist files (*.rpls, *.vpls) are placed; a CLIPINF subdirectory wheremultiple clip information files (*.clpi) are placed; and a STREAMsubdirectory where multiple record data stream files (*.m2ts)corresponding to respective clip information files are placed.

On the other hand, record data stream files recorded in the STREAMsubdirectory, more specifically, various play control information for‘01001.m2ts’ and ‘02002.m2ts’ files are recorded in ‘01001.clpi’ and‘02002.clpi’ files respectively, which are placed in the CLIPINFsubdirectory; playlist information which determines serial playing ofthe ‘01001.m2ts’ and ‘02002.m2ts’ files and order of playing can berecorded in ‘01001.rpls’ file placed in the PLAYLIST subdirectory.

As depicted in FIG. 5, within the playlist files (*.rpls, *.vpls), morespecifically, in the syntax of a real playlist file (xxxx.rpls),recorded are a version number; start addresses of playlist, playlistmark, and maker private data; and playlist of user interface applicationinformation (UIAppInforPlayList) wherein a one bit automatic deletionflag (time_bomb_flag) and corresponding deletion time information(expire_time_info) in accordance with an embodiment of the presentinvention are included. In case the automatic deletion flag is set inorder to prohibit the user's arbitrary unlimited playback or editing ofa clip of A/V stream where copyright protection and security for paymentare needed, deletion time information is added to automatically deletethe corresponding clip of A/V stream. For this purpose, one bitallocated from four bits of reserved area for word alignment bypredetermined record size or from another reserved area can be used asthe automatic deletion flag.

The deletion time information can be added as an absolute timeinformation irrespective of start time of playing or relative timeinformation counted from the start of playing, which automatic deletionflag and information of deletion time can be included in a received A/Vstream. If not included in the received A/V stream, a disc recorder canset up the deletion time and activate the automatic deletion flag. Inthis case, deletion time may be predetermined, for example, ‘after 96hours’.

After recording in this manner, by searching and identifying thedeletion time information which is stored together with the automaticdeletion flag, the optical disc apparatus of VDR system (3) mayautomatically delete the corresponding clip of A/V stream, therebypreventing user's unlimited playback or arbitrary editing thereof, wherethe automatic deletion flag is set to. This procedure is furtherdescribed in the following.

FIG. 6 illustrates the operational flow of the method for managing therecord data streams in a rewritable recording medium according to anembodiment of the present invention. As shown in FIG. 6, when the usersends a play request for a clip of A/V stream (S30) among the clips ofan A/V streams stored in the BD-RW 1, the VDR system 3 may search forthe playlist corresponding to the clip of A/V stream, after which it mayidentify a user interface application information playlist(UIAppInfoPlayList) included therein (S31).

The VDR system 3 may then search for and check the automatic deletionflag (time_bomb_flag) included in the user interface applicationsinformation playlist (S32). If the automatic deletion flag is set to, itmay search for and check the deletion time information(expire_time_infor) linked with the automatic deletion flag (S34).

Thereafter, with reference to the checked deletion time information, ifthe absolute time information which is independent of start time ofplaying, coincides with or precedes the present time (S35), the clip ofA/V system is considered to be a proprietary television program or moviewith copyright protection or payment required, and the A/V stream may bedeleted (S36). If the automatic deletion flag (time_bomb_flag) is notset or the deletion time information (expire_time_info) is set afterpresent time, the VDR system 3 may perform an ordinary play operationupon user request (S37).

On the other hand, if the deletion time information (expire_time_info)is recorded as a relative time information counted from the start of theinitial play of the clip of the A/V stream, elapsed time from theinitial play of the clip of A/V stream may be counted and compared withdeletion time information. Subsequently, when the elapsed time countedfrom the initial play coincides with or exceeds the deletion timeinformation, the A/V stream may be deleted, whereas if the elapsed timecounted from the initial play is less than the deletion timeinformation, the ordinary play operation upon user request may beperformed.

Moreover, by adding an edition protection flag (edit_protect_flag) toprevent partial deletion or unauthorized editing of the correspondingclip of the A/V stream to the user interface application informationplaylist (UIAppInfo PlayList), and thereafter enabling the editionprotection flag and the automatic deletion flag and deletion timeinformation to be related each other, copyright protection and securedpayment for proprietary television programs or movies can be madeeffective.

The foregoing description of a preferred embodiment of the presentinvention has been presented for purposes of illustration. Thus, thoseskilled in the art may utilize the invention and various embodimentswith improvements, modifications, substitutions, or additions within thespirit and scope of the invention as defined by the following appendedclaims.

1. A method for processing digital content, comprising steps of:determining whether or not control information to restrict a length oftime for an access to the digital content is present based on indicationinformation; and controlling access to the digital content based on thedetermining step, wherein the indication information indicates whetherthe control information is present.
 2. The method of claim 1, whereinthe control information includes time information indicating the lengthof time during which access to the digital content is allowed, the timeinformation specifying one of: an absolute time, at which point accessto the digital content will not be allowed, or a relative time from afirst access of the digital content, at which point further access tothe digital content will not be allowed.
 3. The method of claim 1,wherein the step of controlling access to the digital content comprises:analyzing time information included in the control information, if theindication information indicates that the control information ispresent; and determining whether the digital content may be accessedbased on a result of the analyzing step.
 4. The method of claim 3,wherein the analyzing step comprises comparing the time information witha current time.
 5. The method of claim 4, wherein the determining stepcomprises accessing the digital content based on a result of thecomparing step.
 6. The method of claim 4, wherein the determining stepcomprises deciding that the digital content can be accessed if a resultof the comparing step indicates that there is time remaining in whichaccess to the digital content is allowed.
 7. The method of claim 4,wherein the determining step comprises deciding that the digital contentcannot be accessed if a result of the comparing step indicates thatthere is no time remaining in which access to the digital content isallowed.
 8. The method of claim 7, further comprising deleting thedigital content if the result of the comparing step indicates that thereis no time remaining in which access to the digital content is allowed.9. The method of claim 1, wherein the controlling step comprisespermitting access to the digital content if the control information isnot present.
 10. A method of managing a digital content, comprisingsteps of: checking whether time information to restrict a length of timefor access to the digital content is present based on indicationinformation, prior to accessing the digital content, wherein the timeinformation is available only if the indication information specifies arestricted access to the digital content; allowing access to the digitalcontent if the time information is not present, or if the timeinformation is present and access time remains; and not allowing accessto the digital content if the access time does not remain.
 11. Themethod of claim 10, wherein the time information specifies one of: anabsolute time, at which point access to the digital content will not beallowed, or a relative time from a first access of the digital content,at which point further access to the digital content will not beallowed.
 12. The method of claim 10, wherein the indication informationis included in management information, the management informationfurther including version information for identifying a version of themanagement information.
 13. A method of managing digital content,comprising steps of: determining whether indication informationspecifies a restricted access to the digital content; comparing timeinformation with the current time to determine whether the digitalcontent can be accessed if the indication information specifies therestricted access to the digital content as a result of the determiningstep; allowing access to the digital content if the indicationinformation does not specify the restricted access, or if the timeinformation indicates that an access time remains; and not allowingaccess to the digital content if the access time does not remain,wherein the time information indicates the access time, and wherein thetime information is present if the indication information specifies therestricted access to the digital content.
 14. The method of claim 13,wherein the indication information specifies the restricted accessincluding the access time.
 15. The method of claim 13, wherein the timeinformation specifies one of: an absolute time, at which point access tothe digital content will not be allowed, or a relative time from a firstaccess of the digital content, at which point further access to thedigital content will not be allowed.
 16. The method of claim 13, whereinthe indication information is included in management information, themanagement information further including version information forindicating a version of the management information.
 17. The methodaccording to claim 2, wherein the first access to the digital content isa first playback of the digital content.
 18. The method according toclaim 11, wherein the first access to the digital content is a firstplayback of the digital content.
 19. The method according to claim 15,wherein the first access to the digital content is a first playback ofthe digital content.